[3H]-L-Selectride Reduction of 3-one-Steroid A Wyeth-Ayerst Research product contains these steroids as minor, but significant, biologically active components. In order to extend the present patent on this product, it has become critical to identify all the minor components and their bioactivity profiles. Tritiated versions of these steroids were necessary to carry out receptor binding assays and metabolic pathway studies. The most logical method of preparation of one series of components is via a hydride reduction of a ketone. The best reducing agent for this purpose is 3H-L-Selectride, available at the NTLF, which gives a 3:1 ratio of b to a isomers; the b isomer is the desired product. The other series of steroids is also prepared by hydride reduction of a ketone. The best reducing agent for this purpose is sodium borohydride which gives exclusively the desired b isomer.